Claude Fable 5.2 and Claude Mythos 5.2: What's New and Who Gets It

Key takeaway: Anthropic released Claude Fable 5.2 and Claude Mythos 5.2 on 9 November 2026. They are the same underlying model. Fable 5.2 has extra cybersecurity and biology safeguards and is open to everyone on the API. Mythos 5.2 has looser safeguards in those areas and is only for vetted organisations. Both cost $8 per million input tokens and $40 per million output tokens (USD), down from $10 and $50 for the 5.1 versions.

• Who it’s for: Anthropic says Fable and Mythos are for “the most ambitious, open-ended technical work”. For most coding and knowledge tasks it still recommends starting with Claude Opus 5.5.
• Where: the Claude apps on eligible paid plans, the Claude API, Claude Code, Amazon Bedrock, Google Cloud and Microsoft Foundry.

Research-based news. We haven’t tested Claude Fable 5.2, and Mythos 5.2 is verified-access only. Facts come from Anthropic’s own pages and docs, checked 10 November 2026. Prices are in USD and exclude tax.

What Anthropic launched

The launch post is dated 9 November 2026. Anthropic describes both models as “designed to tackle the most daunting technical challenges”. The system card calls them “two configurations of a new large language model”.

• Claude Fable 5.2: for general use. Model ID claude-fable-5-2.
• Claude Mythos 5.2: the same model with more permissive cyber and biology safeguards. Model ID claude-mythos-5-2, for verified organisations only.
• Context window: 1 million tokens, with up to 128,000 output tokens per request, per the Claude docs.
• Input: text and images in, text out.

What’s new, according to Anthropic

Anthropic says the 5.2 models “show improvements in areas like coding, reasoning, and vision”. Its main claims:

• Speed: outputs up to 30% faster than Fable 5.1 and Mythos 5.1.
• Clearer answers: testers found they “communicate more clearly” than earlier Fable and Mythos models.
• Fast mode (optional): up to 2.5 times faster token generation, at a higher price.
• Fewer false blocks: in early testing, Anthropic saw about 55% fewer safety blocks with Fable 5.2 than with Fable 5.1.
• Big projects: Anthropic says that in prerelease testing the models helped design three working electronic devices and formalised the proof of Fermat’s Last Theorem in 30 hours.

All benchmark figures below are Anthropic’s own reported results. We haven’t tested them.

Test (Anthropic’s label)	Fable 5.2	Opus 5.5	Fable 5.1
FrontierSWE v2 (agentic coding)	69.9%	62.3%	56.3%
Humanity’s Last Exam, with tools (reasoning)	74.2%	67.7%	65.6%
Chartography, no tools (reading charts)	73.4%	64.4%	44.8%

On 10 November, Artificial Analysis listed Fable 5.2 (at Max effort) with a score of 65 on its Intelligence Index v5.0.1, ranked #1 of the 74 models on that page’s comparison. The index combines nine tests. The same page rates it slow and verbose, at about $26.54 per index task.

Claude Fable 5.2 pricing (API)

From Anthropic’s pricing docs and the Fable 5.2 docs, USD per million tokens, checked 10 November 2026:

Item	Fable 5.2 / Mythos 5.2	Fable 5.1 / Mythos 5.1
Input	$8	$10
Output	$40	$50
Cache read	$0.20	$0.25
5-minute cache write	$10	$12.50
Batch (input / output)	$4 / $20	—
Fast mode (input / output)	$16 / $80	—

For comparison, the same pricing page lists Claude Opus 5.5 at $4 input and $20 output, half of Fable 5.2’s list price.

Who gets Claude Fable 5.2

In the Claude apps (from claude.com/pricing, checked 10 November 2026):

Plan	Fable access (normal terms)
Free	No
Pro ($20 a month, or $17 a month billed yearly)	Paid with usage credits
Max ($100 a month) and Ultra ($200 a month)	Included, up to 50% of weekly limits
Team	Premium seats: up to 50% of weekly limits; standard seats: usage credits
Enterprise	Yes

Launch-week offer: the Claude Help Center says Pro plans and Team standard seats get all Fable models included in their weekly limits, up to 50%, until 16 November 2026 at 11:59 pm PT, plus one Fable limit reset. Max, Ultra and premium seats get one to three resets, depending on how long they’ve subscribed. Resets only go to accounts with paid billing before 9 November 2026 at 10:00 am PT. The Free plan isn’t included.

On the API and clouds: the Claude docs list Fable 5.2 for all Claude API customers, plus Amazon Bedrock (anthropic.claude-fable-5-2), Claude Platform on AWS, Claude Models on Google Cloud and Microsoft Foundry.

Data retention: Fable 5.2 and Mythos 5.2 require 30-day data retention and aren’t available under zero data retention unless Anthropic expressly authorises it. Check this before sending customer data.

Who gets Claude Mythos 5.2

Mythos 5.2 is not open sign-up. According to Anthropic:

• Cybersecurity professionals can apply through the Cyber Verification Program.
• Life sciences researchers can apply through the Life Sciences Verification Program.
• Claude Enterprise customers can use Claude Security, a code-scanning tool that Anthropic says is now powered partly by Mythos 5.2, without joining a programme.
• Fast mode for Mythos is only for organisations in the verification programmes.

Anthropic also says Fable 5.2’s safeguards “will block most cybersecurity-related tasks”. Blocked cyber queries get an answer from Claude Opus 4.8, and blocked biology queries from Claude Opus 5.

Claude Code Fable 5.2: how to switch

The Claude Code docs say Fable 5.2 needs Claude Code v2.1.321 or later (run claude update). Then run /model fable, or start with claude --model claude-fable-5-2. No Fable model is the default on any plan, so you have to choose it. Claude Code comes with all paid plans, and Fable usage follows the plan rules above. Fable models use your limits faster than other Claude models, Anthropic says.

Fable 5.2 vs Opus 5.5, briefly

On fable 5.2 vs opus 5.5, Anthropic’s own position is clear: start with Opus 5.5 as your “daily driver” and move up to Fable for harder, open-ended work. Fable 5.2 has twice the list price. Anthropic also says that on its FrontierCode 2.0 test, Fable 5.2 at High effort scored about level with Opus 5.5 at Max effort “for roughly half the cost per task”. We’ll cover the full comparison in a separate post.

Why the timing matters

CNBC reports this is Anthropic’s first frontier release since CEO Dario Amodei called in September for a slower pace of AI development. It also lands as Anthropic prepares for its IPO. See our post on Anthropic’s S-1 filing.

What a small team should do

If Opus 5.5 or Sonnet 5.5 already handles your work, you don’t need to switch. If you have a hard, long-running task, such as a large code migration or a deep research report, test Fable 5.2 on that one task. Then compare the cost per finished job, not just the price per token. New to Claude? See our ChatGPT vs Claude vs Gemini comparison.

A stronger model only helps once it’s part of real work. AIFix Automation can connect a model like this to your intake, follow-up and reporting steps, on accounts in your name. That’s our own service.

FAQ

What is Claude Fable 5.2?

It’s Anthropic’s newest top-tier Claude model, released on 9 November 2026 for demanding reasoning and long-running agent work. API ID: claude-fable-5-2.

What is the difference between Claude Fable 5.2 and Claude Mythos 5.2?

They’re the same underlying model. Fable 5.2 has stronger cyber and biology safeguards and is generally available. Mythos 5.2 has looser safeguards in those areas and is only for verified organisations.

How much does Claude Fable 5.2 cost?

On the API: $8 per million input tokens and $40 per million output tokens (USD). Fast mode is $16 and $80. In the apps, it depends on your plan.

Can I use Claude Fable 5.2 for free?

Not on the Free plan. Pro and Team standard seats have it included until 16 November 2026, 11:59 pm PT. After that, Pro uses paid usage credits.

What is the Claude Fable 5.2 context window?

1 million tokens, with up to 128,000 output tokens per request.

Can I get Claude Mythos 5.2?

Only through Anthropic’s Cyber or Life Sciences Verification Programs. Claude Enterprise customers can also use it through Claude Security.